The performance of a hard disk drive is dependent on the positional accuracy of a digital servo controlled motor controller. The motor controller is used to position the read/write heads (or transducers) as its corresponding spindle motor rotates the magnetic disk media. In addition to the spindle motor, the motor controller may utilize a voice coil motor for positioning the read/write heads over the disc surfaces until the heads are positioned over the desired track. The servo controlled motor controller may utilize the positional information embedded in the servo sectors of a track to position or reposition the heads, as the magnetic disk media continuously rotates. Typically, this positional information is sampled once per servo sector. Accordingly, positional adjustments may be made once per servo sector.
When a serial port is used in the hard disk drive to transmit positional updates to a voice coil motor (VCM) of its motor controller, its ability to adjust its heads may be affected by any delay or interruption that prevents a positional update from reaching the VCM. The delay or interruption may be attributed to data transmissions that are unrelated to repositioning the read/write head using servo sector positional information. Such delays or interruptions may result in significant “jitter” of the read/write head of the hard disk drive, resulting in poor hard disk drive performance. Ultimately, this jitter may generate read and/or write errors during operation of the hard disk drive.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.